Cabinet Depth and What Actually Fits

Storage is sold by volume and used by reach. A cabinet you cannot see into is a cabinet whose back half holds things you have forgotten you own, which is why depth is the dimension most worth thinking about and least often questioned.

What common items need

Item	Internal depth
Paperbacks	150 mm
Hardbacks	250 mm
A4 box files, upright	320 mm
Dinner plates, stacked	300 mm
Vinyl records	330 mm
Folded clothes	350 to 400 mm
Hanging clothes on a rail	550 to 600 mm

Almost everything on that list fits inside 400 mm. The exception is hanging clothes, which is why wardrobes are deeper than everything else and why a 450 mm cabinet cannot be one.

The 450 mm case

450 mm external is roughly 410 to 425 mm internal after the door and the back panel. That takes:

• Box files upright with space to get fingers behind them.
• Plates, bowls and serving dishes in a single row.
• Folded clothes.
• Records, vertically, with room for the sleeve edges.
• Most kitchen appliances that are not a stand mixer.

The Steel Cabinet is 900 mm wide, 450 mm deep and 1800 mm tall in welded 2 mm steel, with two doors and three shelves. That depth is the deliberate middle: enough for files and crockery, not so much that things disappear behind other things.

Why deeper gets worse

Past about 450 mm, three things happen.

1. Two rows. You start storing in front of and behind. The back row becomes invisible, and invisible storage is where things go to be bought again.
2. Reach. Getting to the back of a 600 mm cabinet on a high shelf means moving the front row first. Within a month people stop bothering.
3. Floor. Every 100 mm of depth on a 900 mm wide cabinet takes another 0.09 square metres of floor, and in a hallway or small room that is the difference between a comfortable passage and a squeeze. See sizing furniture for a narrow hallway.

Width and height are the better levers

If you need more storage, go up or sideways before you go deeper. A taller cabinet keeps everything one row deep and visible. A wider one does the same.

The limit upward is reach, not structure. Above about 1800 mm you need a step for the top shelf, which means the top shelf stores seasonal things. That is a legitimate use, as long as you plan it that way rather than discovering it.

Internal, not external

Published dimensions are external. The number that holds your things is internal, and the difference is the door, the back panel and any frame.

• Door and clearance: 25 to 40 mm.
• Back panel: 5 to 20 mm.
• So a 450 mm external cabinet gives roughly 400 to 420 mm usable.

Measure the thing you most want to store, add 20 mm, and check it against internal depth rather than the catalogue figure.

Door swing

A cabinet 900 mm wide with two doors has doors around 450 mm each, and each sweeps a 450 mm arc into the room. In a corridor, that arc is the real footprint.

Work out whether the doors can open fully where you intend to put it. In tight spaces, two narrow doors beat one wide one, and sliding doors beat both at the cost of only ever reaching half the cabinet at a time.

Weight and the wall

A tall cabinet is a tipping risk when loaded high and opened. Fix it to the wall if there is any chance of a child climbing it, and load heavy things low. The Steel Cabinet is 62 kg empty, which helps, and it still wants levelling so that the doors hang true. A cabinet on an uneven floor has doors that drift open, which is the first sign to look for.

Floor loading in an apartment is covered in heavy furniture and floor load in apartments.

Reality check

• Nearly everything fits in 400 mm except hanging clothes.
• Depth beyond 450 mm buys you a second row you will not use.
• Grow up and sideways, not deeper.
• Internal depth is 30 to 50 mm less than the number on the page.
• Door swing is part of the footprint in any narrow space.